Process of increasing permeability of sands and strata



y 1944- c. H. BENCKENSTEIN 2,354,570

PROCESS OF INCREASING FERTZEABILITY CI" SANDS AND STRATA Fiiled March 28, 1941 grwmwb- Patented July 25, 1944 PROCESS OF INCREASING PER'MEABIIJTY OF SANDS AND STRATA Charles Height Benckcnstein, Vinton, Ia. Application March 23, 1941, Serial No. 385,764

1 Claims. (01. 166-21) This inventor relates to a process for increasing the permeability of sands, shales and other strata, particularly as applied to oil, gas and other mineral wells and mines.

This application is a continuation-in-part of my co-pending application Serial No. 289,857, filed August 12, 1939, now abandoned.

One of the objects of the present invention is to provide a process for the enlargement of the intersticial passages in said strata by the abrasive action of sharp particles forcibly carried through said passages into cutting contact with the walls thereof in a vehicle of flowing liquid.

Inasmuch as the said passages generally become smaller as they recede from the well, and as they ramify from the larger passages, the invention contemplates first sending very small abrasive particles into the passages with the liquid vehicle, following them with larger abrasive particles and then still larger abrasive masses whereby the cross-sections of the entire system of passages is increased and the enlargement of the ultimate passages is progressively extended away from the well.

Another object of the invention is to repetitively apply forced flow of the abrasive carrying liquid to the strata, alternating with periods of pressure release, resulting in back flow, whereby the walls of the passages are repeatedly scoured by the abrasive, resulting in further emciency in the enlargement of the interstices.

Other objects and purposes of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

In the drawing:

Figure 1 represents a well, showing circulation of fluid and abrasive material into the desired strata or formation;

Figure 2 indicates the bottom of a well bore with screen adjacent to a strata treated in accordance with this inventive concept;

Figure 3 is an arrangement showing a perforated casing in a properly treated stratum; and

Figure 4 indicates a completed well treated in accordance with this invention.

In carrying out .the process of the present invention, liquid is forced back into the sand, shale or other strata, and as the fluidpenetrates such formation, abrasive material such as sand, gravel, iron, steel, glass, etc., in very small particles is added to the liquid and carried by the liquid under pressure into such formation, the small abrasive particles passing'into the minute their cutting action against the walls thereof. The abrasive material added to the liquid is gradually increased in size, so as to come into cutting contact with the walls of the larger passages to increase the size thereof. In the event that the formation is very dense, close or tight, the pressure of the liquid may be first suddenly released to cause heaving of the formation for the purpose of opening up the passages to permit the abrasive laden liquid vehicle to pass into said formations.

In applying the process of the present invention, it is generally desirable to first clean the formation. For this purpose, liquid is first applied to the well without the addition of any abrasive for the purpose of washing out the mud. After this washing out step, the packer on the bottom of the wash pipe is expanded to seal between the wash pipe and the casing. After the liquid is found to be passing into the formation, then the small grains of cutting material are added and from time to time the size of these granules is increased until the formation has been permeated, penetrated and enlarged to the desired suiilciency.

It may be desirable periodically to release the pressure upon the liquid vehicle so as to produce a back flow, bringing the abrasive materials into cutting action against the walls of the passages in reverse direction, and to re-apply the pressure, repeating these alternate pressure and release phases as often as may be desired. At the end of the process it is desirable for the support of the walls of the larger' passages and including the sides of the well, to leave the large particles of material in the passages and to fill the well with large materials to the desired height in the casing. At the end of the process the wash pipe is withdrawn under pressureand a slotted plug is inserted while the well is still under pressure, on top of the material which fills the well, where it is permanently anchored so as to hold the material in place in the well.

In case a screen or other straining device is used, the formation is permeated as above described. A column of mud fluid under pressure is then introduced into the well to hold the material in place; the wash pipe is removed under pressure, and the straining device is inserted while the formation remains under pressure. The well may be then washed and sealed in customary manner.

In the event that it is desired to put a casing in the well and perforate it in situ, the perforainterstices or passages, enlarging the same by ll tion is made in the usual manner by directi a enlarged passages through jet of abrasive laden mud against the wall of the casing at the level of the fissure to be penetrated under the customary mud pressure in the well, until the perforation has been accomplished. Then the well is sealed oil above the perforation, either by the packer, or at the mouth of the well, and the abrasive stream, under pressure superior to that of the oil head, is pumped into the fissure against the oil head. First, small cutting materials are added, then larger cutting materials. Periodically, the pump pressure is released and the oil head permitted to react, pushing the abrasive stream in the reverse direction through the fissure. This repetitive reversal in the direction of movement of the abrasive stream within the fissure, is continued until the formation has been sufliciently enlarged.

Referring in detail to the figures, in Figure I a well casing H) penetrates the ground [2 through successive strata, until it reaches the oil bearing stratum M, which according to the present invention is to be permeated to increase the size of the system of intersticial passages to provide for greater oil production. In Figures 2 and 3 the lower end of the bore hole is indicated. In Figure 2 a tubing I6 carries a screen It at its lower end, of well-known construction, which is packed off at 20. In Figure 3 the casing in extends to the lower end of the bore hole at the bottom of the strata, and has been perforated as at 22 to provide the necessary ports for the passage of the liquid.

In Figure 4 the process is shown as having been completed, and the bottom of the bore hole and casing have been filled to a predetermined depth by large materials 24, which are permanently anchored in place by means of a perforated plug 26. These particles of large material 24 allow outflow of oil between them for passage upward through the perforations in the plug. The particles 24 serve to sustain the walls at the bottom of the bore and are held from upward displacement under oil pressure by'the plug.

The upper end of the casing is provided with the usual casing head 28 or Christmas tree arrangement having one or more throttle valves 30 to control the flow of liquid, either into or out of the well.

With. the parts as indicated in Figure 1, the process as herein outlined is followed and the small abrasive particles are injected into the strata by introducing them into the tubing or pipe 32 along with the liquid flowing under pressure, said smaller particles by their abrasive ac- Although a preferred embodiment of this invention is illustrated and described, variations within the true spirit and scope of the same are permitted by the terms of the appended claims.

What I claim as my invention is:

1. Method of increasing the permeabil ty of gas or oil bearing stratum by attrition comprising forcing through passages in said stratiurz a column of liquid charged with abrasive particles, and repetitively reversing the direction or how oi said column. of liquid through said passages.

2. Method of increasing the permeability of a gas or oil bearing stratum comprising forcing tion scouring the walls of the passages, and particularly the smaller passages, thereby enlarging them. The introduction of cutting materials of gradually increasing sizefollows, which more efificiently scour the walls of the larger passages, thus leaving the stratum filled with a system of which the oil or gas may flow freely toward the bore hole of the well.

The process herein contemplated is especially adapted for use not only in enlarging the intersticial passages in sand, shales, and other strata, but for introducing into said passages supporting bodies which hold in place the walls of said passages and at the same time provide ample spaces between the abrasive particles and masses for the free flow of oil or gas toward the well. The

process is especially adapted for increasing the 3 production or recovery of oil, gas, and other fluid minerals'or chemicals from a stratum.

through said stratum a liquid bearing successive charges of abrasive particles, the particles of each successive charge being of larger size than the particles of the preceding charge.

3. Method of increasing the permeability of a gas or oil bearing stratum by increasing the cross-sectional dimensions of the system of intersticial passages through said stratum opening into a well, comprising forcing into said well and from and through said passages, a column of liquid, and adding to said liquid column successive charges of abrasive particles, the particles of each successive charge being of larger size than the particles of the preceding charge.

4. Method of increasing the permeability of a porous gas or oil bearing stratum comprising increasing the porosity of said stratum by forcing through the pores a liquid vehicle containing a charge of fine abrasive particles followed by a liquid vehicle containing a charge of larger abrasive particles whereby the size of said pores is increased.

5. Method of increasing the permeability of a porous oil or gas bearing stratum comprising forcing through the said stratum against the stratum pressure a liquid vehicle bearing successive charges of abrasive particles, the particles of each successive charge being of larger size than the particles of the preceding charge, releasing the pressure to permit reverse flow of the liquid with the abrasive particles under stratum pressure, and re-applying pressure to said liquid.

6. Method of increasing the permeability of a gas or oil bearing stratum by increasing the crosssectional dimensions of the system of intersticial passages through said stratum comprising forcing through said stratum a column of liquid having a leading portion charged with abrasive par.- ticles of relatively small size and a following portion charged with abrasive particles of relatively large size, and leaving the particles of relatively large size'in situ in the larger passages in wall supporting relation thereto.

7. Method of increasing the permeability of a gas oroil bearing stratum by increasing the crosssectional dimensions of the system of intersticial passages through said stratum comprising forcing through said stratum against stratum pressure a column of liquid having a leading portion charged with abrasive particles of relatively small size and a following portion charged with abrasive particles of relatively large size, releasing the pressure to permit reverse flow of liquid with the abrasive sure, repeating the cycle of flow reversals, and finally leaving the particles of relatively large size in situ in the larger passages in wall supporting relation thereto.

. CHARLES HEIGHT BENCKENS'I'EIN.

particles, under stratum pres-' 

